supreme court is deciding on whether a controversial arizona law is valid. some say it tries to keep immigrants from voting and national elections. ktvu looks at the issue and tells us why some say the law actually makes it harder for legal citizens to vote. >> reporter: voting is a light only granted to u.s. citizens but in arizona the attorney general wants to guarantee that election fraud won't occur and that illegal immigrants won't try to vote in federal elections. >> we have a right to require additional information to satisfy ourselves that someone is a citizen. >> right now arizona requires proof of citizenship like a drivers license to register to vote in state elections. the supreme court will decide whether or not the state can demand proof of citizenship on federal voter registration forms. the supreme court heard arguments from both sides this morning. >> specifically whether congress has the ability to provide for a simple male voter registration form that can be used in any state. this is about the basic right to vote. >> here in california yo